Agricultural machines such as high-clearance sprayers are getting larger and more complex, with some sprayers having four-wheel steering to improve maneuverability, such as when making tight turns in a field's headlands. Such four-wheel steering systems typically have a controller that electronically controls a single steering valve which meters hydraulic fluid to both hydraulic rear-steering cylinders to correspond to a front-steering input. However, this shared steering valve for controlling both rear-steering cylinders can require cumbersome hydraulic hoses or lines. Such hydraulic hoses have to interconnect the shared steering valve to each of the steering cylinders, as well as to the underlying hydraulic circuit's pressure and tank lines, which can consume substantial space and cause difficulty to route. A need therefore exists for an improved system which eliminates one or more of the foregoing disadvantages.